The park's abundant wildlife includes raccoons, foxes, opossums, bobcats, skunks and squirrels. Late in the day, with binoculars, you can count the deer in the hill areas adjacent to the parking lot. Las Trampas is Spanish for "The Traps" or "The Snares." According to Erwin G. Gudde's California Place Names, traps were once set in the chaparral of the hills to catch elk. Historical records also indicate that antelope and mountain lions were plentiful during the last century. Sightings of the big cats have been reported in recent years.

The East Bay Regional Park District leases some of the grassland areas for cattle grazing. Cattle keep the grass height down, which lessens the fire hazard during the dry season.